# Multicast discovery sometimes fails **URL:** \ **Category:** Elasticsearch\ **Created:** [October 2, 2013, 10:18am UTC](https://discuss.elastic.co/t/multicast-discovery-sometimes-fails/13823 "2013-10-02T10:18:31Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Urs](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/urs/32/2074_2.png) [@Urs](https://discuss.elastic.co/u/Urs)\ **Post date:** [October 2, 2013, 10:18am UTC](https://discuss.elastic.co/t/multicast-discovery-sometimes-fails/13823/1 "2013-10-02T10:18:31Z")
Hello, I have two nodes, 0.90.3, CentOS 6.4 on vSphere 5.1U1. Both machines have two networks. An access VLAN (172.31.120.0/24) and a separate VLAN for all replication/internal ES traffic (10.105.1.0/24) At the beginning it just worked fine. But then, sometimes, if i restart one node, it doesn't discover the other node anymore. I already have set "network.publish\_host: 10.105.1.x" on both nodes from the beginning, because i wanted to have all this traffic on the separated VLAN. I can restart the service or machine as many times i want, it doesn't work anymore. After some time it can happen that it starts working again when restarting ES. Haven't found a way to reproduce this. Then I set "discovery.zen.ping.unicast.hosts: ["10.105.1.x"]" on the node which wasn't able to rejoin the cluster and than it worked again. Changing it back, doesn't work... Very strange. I thought ES uses the network defined on publish\_host only for discovery if it is defined. Am i wrong with that? Would like to use multicast instead of unicast if possible, but i have to be sure it works correctly. Thank you Urs -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![spinscale](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/spinscale/32/25011_2.png) [@spinscale](https://discuss.elastic.co/u/spinscale)\ **Post date:** [October 6, 2013, 4:01pm UTC](https://discuss.elastic.co/t/multicast-discovery-sometimes-fails/13823/2 "2013-10-06T16:01:19Z")
Hey, can you increase the log level and check the logfiles maybe, if that gives you more information? Would be interested to know more in your case... --Alex On Wed, Oct 2, 2013 at 12:18 PM, Urs [uweiss@icrcom.com](mailto:uweiss@icrcom.com) wrote: > Hello, > > I have two nodes, 0.90.3, CentOS 6.4 on vSphere 5.1U1. Both machines have > two networks. An access VLAN (172.31.120.0/24) and a separate VLAN for > all replication/internal ES traffic (10.105.1.0/24) > > At the beginning it just worked fine. But then, sometimes, if i restart > one node, it doesn't discover the other node anymore. I already have set > "network.publish\_host: 10.105.1.x" on both nodes from the beginning, > because i wanted to have all this traffic on the separated VLAN. I can > restart the service or machine as many times i want, it doesn't work > anymore. After some time it can happen that it starts working again when > restarting ES. Haven't found a way to reproduce this. > > Then I set "discovery.zen.ping.unicast.hosts: ["10.105.1.x"]" on the node > which wasn't able to rejoin the cluster and than it worked again. Changing > it back, doesn't work... > > Very strange. > I thought ES uses the network defined on publish\_host only for discovery > if it is defined. Am i wrong with that? > Would like to use multicast instead of unicast if possible, but i have to > be sure it works correctly. > > Thank you > Urs > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 2:13am UTC](https://discuss.elastic.co/t/multicast-discovery-sometimes-fails/13823/3 "2017-07-06T02:13:32Z")